Is your memory playing tricks?

Is your long term memory playing tricks on you? And is that really such a bad thing?

Most of us have an earliest memory. Mine is of a bee sting at the age of four. I was outside the kitchen when the bee attacked, and I recall crying for hours in my mother's arms. Or did I? New US research is shining a torch on childhood memory and its authenticity. According to the research, human memory is incredibly fragile and inventive, and we easily create false memories of our past, some of which have long-term effects on our behaviour. In my case, while my mother doesn't recall the event, I was left with a lifelong fear of bees.

What's more, we're surprisingly open to suggestion. In a series of experiments, researchers falsely suggested that the participants fell ill after eating egg salad sandwiches as children. Those participants were consequently turned off egg salad sandwiches, even though the memory was false.

So what can we trust of our memories? And how do we know which ones are real? "I don't think we can know," says memory expert Dr Kerry Chalmers, deputy head of psychology at the University of Newcastle. "It's hard to distinguish between the truth and what we've added to the memory. You might think you have a vivid memory of something, say, where you were on September 11.

But the research has shown that we're not as good as we think we are." (In fact, research on September 11 memories shows that the personal details around that event are frequently inaccurate.) Dr Chalmers believes some of us are more suggestible to memory distortion, a la the egg sandwich, than others. "There's a personality difference," she says. "Some of us will not accept things like that, and some of us will."

The power of memory

Memory is the process by which we encode, store and retrieve information. "Everything we do relies on memory," Dr Chalmers says. "What we learn becomes our memory if we remember it - from tying your shoelaces to recalling where you put your keys. We couldn't function without memory."

Remembering the events of your life is called "autobiographical memory" and usually kicks off between the ages of three and four. These memories are generally fleeting and vague, and it's not until after the age of seven that memories become a continuous narrative.

Sigmund Freud believed we repress early memories because they are too painful, but most scientists today believe that "infantile amnesia" is more biological. Before age three, the brain's hippocampus (which plays a crucial role in binding memory) is not developed enough. Others say it's connected to language development: once we can talk, we can shape events into a story that can be retold and remembered.

What is certain is that memories can be incredibly powerful. "In a way, memory is like a web woven from sounds, smells, tastes, touches and sights," say Dr Jo Iddon and Dr Huw Williams in Memory Booster Workout (Hamlyn).

Memories can uplift and inspire or cause lifelong phobias, behavioural problems and depression. Then there are repressed memories, where therapists help a patient to "unblock" a past memory. This has dangerous implications, Dr Chalmers says. "We call it the false memory paradigm. A study found that people with repressed memories recalled under therapy were much more prone to false memory than others."

Most memories erode with age. "Elderly people and people with dementia do start to confabulate," says Dr Chalmers, "so if they don't remember the full details, they may fill in the gaps rather than say they don't know."

Some memory loss is a good thing, say Iddon and Williams. "Without forgetting, your head would be spinning, with far too much information in it. Forgetting is ... crucial to remembering, since you need to free up your memory for the things you want or need to remember."

How to test your memory

Keen to verify those cherished childhood memories? Here are some things that might help:

Supporting evidence: photos, letters, films, dairy entries, newspaper archives, leases, class photos and report cards can all help date and verify memories. Photos can be deceiving, though, warns Dr Kerry Chalmers. "If you've got a picture of your fifth birthday cake with a doll on it, how do you know if you remember that birthday or if you've seen the photo through time?"

Conversations: family, friends and neighbours can help fill in the blanks, but again, proceed with caution: "Parents may even get confused about which sibling it happened to, so don't necessarily rely on them," says Dr Chalmers.

Detail: the more vivid an early memory, the more likely that it has been embellished over time. (Studies show that as the brain ages, it loses its ability to recall specifics faster than its ability to recall impressions).

Memory sticks

You're more likely to remember something if ...

It left you truly happy or sad, not with mixed emotions or ambivalence.

It's rehearsed regularly and elaborated upon with rich, colourful details.

You're in your late teens or early 20s, a time when memory peaks.

You're highly social and interact richly with others (this also slows down memory decline).

You're European: evidence shows members of more self-focused western cultures have better earlier memories than Asians.

You're a first-born and your parents had more time to have elaborate conversations with you.

You're a woman: a Swedish study found that women tend to have better "episodic memory" based on personal experiences than men.

You work at it! Memory is a network of connections, so if you can't recall your year one teacher, remember your classroom and work back from there.

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